JPH1183474A - Distance measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distance measuring device that can acquire the distance measuring information quickly and accurately while preventing the time for measurement from becoming too long. SOLUTION: The distance measuring device is equipped with an active system measuring means which projects a beam of light onto an object to be measured and calculates the distance from the object by receiving the beam of light reflected by the object, and a passive system measuring means, which calculates the distance from the object on the basis of the object image of received light formed by external light component. Depending upon the service conditions of an applicable optical apparatus, the arrangement includes a control means (#110→#111 or #110→#112→#113) to control the operation of the active system measuring means and passive system measuring means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a distance measuring apparatus having an active type and a passive type distance measuring means and used for an autofocus camera or the like.

[0002]

2. Description of the Related Art As a so-called hybrid type distance measuring apparatus, as disclosed in Japanese Patent Application Laid-Open No. Hei 7-167646, if the external luminance is high, a passive distance measurement result is adopted and low luminance is adopted. If this is the case, the result of distance measurement by the active method is adopted.
As proposed in Japanese Patent No. 7, there is known a method that employs an active method when the distance measurement result is closer to a predetermined value, and uses a passive method when the distance measurement result is more than a predetermined value. I have.

[0003]

However, the hybrid distance measuring device proposed above makes use of the advantageous characteristics of each of the active and passive distance measuring methods to accurately determine the distance to the object to be measured. It is expected to measure distance.

In general, an active-type distance measuring apparatus can perform accurate distance measurement relatively irrespective of subject conditions. However, a distance-measuring object at a long distance and a pulse-shaped object projected from a light projecting unit are used. For a distance-measuring object whose reflectance of the light beam is extremely low, since the pulse-like light beam reflected by the distance-measuring object is small, the signal obtained by photoelectrically converting it with the photoelectric conversion element is also small. It is known that an erroneous distance measurement result may be output under the influence of noise.

On the other hand, a passive type distance measuring device can accurately measure a long distance measuring object without depending on the distance of the distance measuring object, but has poor contrast. It is known that an erroneous distance measurement result is output for an object or a distance measurement object that repeats a similar contrast pattern.

Therefore, in the proposed device of Japanese Patent Application Laid-Open No. 7-167646, the distance measurement result by the passive method is adopted uniformly when the external luminance is high, and the distance measurement result by the active method is used when the external luminance is low. Since the distance measurement method is used uniformly, the weak points of the distance measurement methods that are not good for the distance measurement target remain as they are, and there is a possibility that an incorrect distance measurement result may be output.

In the proposed device of Japanese Patent Application Laid-Open No. 7-167647, if the distance measurement result is smaller than a predetermined value, the active distance measurement result is employed uniformly, and if the distance measurement result is farther than the predetermined value, the passive measurement method is uniformly employed. Since the distance result is adopted, it has the same drawbacks as above.

In other words, in the above-mentioned conventional apparatus, each of the distance measuring methods does not sufficiently cope with a weak distance measuring object.
The advantages of the hybrid ranging method could not be fully utilized.

In view of the above, in any case, the distance is measured by the active method and the passive method, and the distance to the object to be measured is obtained from each of the obtained distance measurement results to obtain an accurate distance measurement result. However, in this case, the time required for the distance measurement becomes longer, and a problem such as a missed shutter chance occurs. In particular, in the case of performing multi-point distance measurement for measuring a distance in a plurality of directions, the distance measurement time is significantly increased.

(Object of the Invention) An object of the present invention is to provide a distance measuring apparatus which can prevent the distance measuring time from being unnecessarily prolonged and can obtain accurate distance measuring information in a shorter time. Things.

[0011]

In order to achieve the above object, the present invention according to the first to sixth aspects of the present invention projects light toward an object to be measured, and the projected light is projected on the object to be measured. Active distance measuring means that calculates the distance to the object to be measured by receiving reflected light from the outside, and passive type distance measuring means that calculates the distance to the object to be measured by receiving external light. A distance measuring device having a distance measuring means, wherein the distance measuring device has control means for controlling the driving of the active distance measuring means and the passive distance measuring means in accordance with the use conditions of the optical equipment. is there.

Specifically, for example, when the focal length information of the photographing lens is on the wide angle side, the distance measuring capability is calculated by using the active type distance measuring means because the distance measuring capability at a long distance is unnecessary. . On the telephoto side, on the other hand, the distance measurement information is calculated by the passive distance measurement means that does not cause a decrease in the distance measurement capability even at a long distance, and the passive distance measurement means has a weak distance measurement target. Therefore, the distance measurement information is also calculated at the center distance measurement point by the active multi-point distance measurement means to obtain the final distance measurement information.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is a block diagram showing an electrical configuration of a main part of a camera having a hybrid distance measuring apparatus according to an embodiment of the present invention. The distance measuring device incorporated in this camera calculates the distance to the object to be measured based on the principle of triangulation, and includes light emitting means for repeatedly projecting a pulsed light beam to the object to be measured. An active type distance measuring device comprising a light receiving means for receiving the pulsed light beam reflected by the object to be measured, and an external light formed in the light receiving section by inhibiting the operation of the light projecting means. This is a hybrid distance measuring device composed of a passive distance measuring device for performing a passive distance measurement from a signal image of a distance measuring object by a component, and is described in detail in Japanese Patent Application No. 8-32510 by the present applicant. This is a configuration using a skim CCD.

In FIG. 1, reference numeral 1 denotes the structure of the light receiving means. Reference numerals 2R and 2L denote sensor arrays composed of a plurality of photoelectric conversion elements, which perform photoelectric conversion in accordance with the amounts of incident signal light and external light components, and output electric charges. Reference numerals 3R and 3L denote image signal accumulation circuits for accumulating the charge outputs of the sensor arrays 2R and 2L, and are constituted by skim CCDs. Reference numeral 4 denotes a signal switch for selecting a signal output from the image signal storage circuits 3R and 3L. Reference numeral 5 denotes an A / D converter, which is an image signal accumulating circuit 3R, 3R, inputted via the changeover switch 3.
The signal charges of the sensor arrays 2R and 2L accumulated in 3L are sequentially A / D converted and transferred to the CPU 6. Reference numeral 6 denotes a CPU for controlling the operation of the entire distance measuring apparatus. When information from the outside is input via the information input member 7, an optimal distance measuring mode is selected and each unit is appropriately operated. The distance to the object to be measured is calculated and obtained, and the result is output to an external device (not shown) via the distance measurement result output circuit 8.

Reference numeral 9 denotes a memory circuit for storing A / D conversion data of signal outputs of the sensor arrays 2R and 2L stored in the image signal storage circuits 3R and 3L and a distance to a distance measuring object. It is used for temporary storage of data when performing. 10 is a triple iRE described later
An iRED drive circuit that controls lighting of D11, and appropriately turns on a light emitting unit (iRED) selected according to the distance measurement mode selected by the CPU 6. Reference numeral 11 denotes a triple iRED having a plurality of light emitting units (iRED), which constitutes a light projecting unit together with the iRED drive circuit 10. In the present embodiment, the triple iRED includes three light emitting units. Things. Note that the number of light emitting units is not limited to three, but may be appropriately determined according to the distance measurement range of the distance measurement device.

Reference numeral 20 denotes a light projecting lens for condensing the light emitted by the triple iRED 11 to form a light beam;
L is a signal light (at the time of distance measurement by an active method) in which the light beam is reflected by a distance measuring object (not shown) or a reflected light of the object to be measured which is exposed to external light (at the time of distance measurement by a passive method). This is a light receiving lens for condensing light and forming a signal image on the sensor arrays 2R and 2L.

In this embodiment, the distance measurement by the active method is performed by operating the iRED
The RED 11 emits light sequentially in three directions, and the signal light reflected by the object to be measured is received by the light receiving lenses 21R and 21L.
Then, the distance to the object to be measured is calculated from the relative distance of the signal image formed here, and the distance to the object to be measured in each direction is obtained. In the passive distance measurement, the operation of the iRED drive circuit 10 is stopped, the triple iRED 11 is turned off, and the reflected light of the object to be measured, which is exposed to external light, is reflected by the light receiving lenses 21R and 21L to the sensor array 2R. , 2L, the distance to the object to be measured is calculated from the relative distance of the signal images formed by focusing. Therefore, it has a function as a hybrid distance measuring device.

The operation when the distance measuring apparatus having the above-described configuration is mounted on a bifocal camera capable of switching the focal length of the taking lens between the wide-angle side and the telephoto side will be described below.

FIG. 2 is a perspective view showing the appearance of the camera. In FIG. 2, reference numeral 30 denotes a shutter button. When the shutter button is gradually depressed, the switch SW1 is turned on first from OFF, and when it is further depressed, the switch SW2 is turned on. Has a two-stage switch configuration in which the switch from OFF to ON. Reference numeral 31 denotes a portion called a front panel, which is made of a transparent material such as glass, and inside which a finder optical system and a distance measuring device are arranged. The light projecting lens 20 and the light receiving lenses 21R and 21L of the distance measuring apparatus shown in FIG. 1 are installed inside the front panel 31. 32
Denotes a lens barrel, which extends in the direction of the arrow, and changes the focal length of the photographing lens. The extended state is the telephoto side, and the extended state is the wide-angle side.
Reference numeral 33 denotes a focal length changeover switch for switching the focal length of the photographing lens, which corresponds to the information input member 7 shown in FIG. 1. By operating the switch, the lens barrel 32 moves in the direction of the optical axis, and It is possible to switch between telephoto and focal length. Reference numeral 34 denotes a flash light emitting unit, and reference numeral 35 denotes a display unit for displaying photographing information such as the number of films.

FIG. 3 shows the operation of the camera having the above configuration.
And the flowchart of FIG.

In step # 101 of FIG. 3, it is determined whether or not the switch SW1 has been turned on by operating the shutter button 30, and if not, the process stands by in this step. Thereafter, when the switch SW1 is turned on, step #
The process proceeds to step 102, where the distance to the subject is measured by a distance measuring device incorporated in the camera. The details of this step will be described later with reference to FIG.

In the next step # 103, the distance measurement result is output to a lens driving device (not shown) via the distance measurement result output circuit 8, and the focusing of the photographing lens 12 is performed based on the result. In the next step # 104, the brightness of the subject is measured using a photometric circuit (not shown). Then, in the next step # 105, the above step #
From the measurement result obtained in step 104, it is determined whether or not the brightness of the subject is brighter than a predetermined value.
Then, the process goes to 6 to drive the strobe circuit to charge a main capacitor (not shown) of the strobe device. When the predetermined charge is charged, the charging is stopped, and the process proceeds to step # 107. On the other hand, if the subject is brighter than the predetermined value, the process immediately proceeds to step # 107.

In step # 107, it is determined whether or not the shutter button 30 is further depressed to turn on the switch SW2. If not, the process waits until it is turned on. Thereafter, when the switch SW2 is turned on, step #
The process proceeds to step 108, where the shutter is opened and closed so as to give an appropriate exposure amount to the film (not shown) based on the brightness of the subject measured in step # 104. At this time, if the main capacitor of the strobe circuit is charged via step # 106, the strobe light is emitted to obtain an appropriate exposure.

In the next step # 109, the film (not shown) is wound up to prepare for the next photographing. The photographing operation for one frame ends here.

Next, the distance measuring operation executed in step # 102 will be described with reference to the flowchart of FIG.

If it is determined in step 101 that the switch SW1 has been turned on, the process proceeds to step # 102, as described above. First, in step # 110, the current focal length of the photographing lens 32 is detected by means not shown. If it is on the wide angle side, the process proceeds to step # 111 to perform distance measurement by the active method, and if it is on the telephoto side, the process proceeds to step # 112 to perform distance measurement by the passive method. Transition.

In step # 111, the photographing lens is on the wide angle side, and the hyperfocal distance is relatively short because the photographing lens has a large depth of field. That is, it does not require a long distance measuring capability. Therefore, at the time of wide angle, the distance to the subject is obtained by multi-point distance measurement by the active method which has few subjects that are not good at the wide angle.

Specifically, the triple iRED 11 shown in FIG.
Are sequentially turned on via the iRED drive circuit 10. FIG. 5A shows the relationship between iRED and the distance measurement range viewed from the viewfinder. First, the central iRED is stored in the image signal storage circuit 3.
Lighting is continued until predetermined signal charges are accumulated in R and 3L. However, when the signal is weak, such as when the subject is at a long distance, it takes a long time to reach the predetermined charge amount, and the distance measurement time itself is prolonged. I have. The limited time is set as the maximum accumulation time and is set to t3 here. Subsequently, the charge stored in the image signal storage circuits 3R and 3L is guided to the A / D converter 5 by switching the signal changeover switch 4 respectively, where it is A / D converted and taken into the CPU 6 as an image of the subject.
From the relative image shift amounts of the two signal images on the sensor arrays 2R and 2L and the optical distance relationship between the light receiving lenses 21R and 21L, the distance to the signal image is calculated in a known manner. If a signal image cannot be obtained even if signal accumulation is continued until the maximum accumulation time t3, it is determined that the subject is at a very long distance, and the distance is set to infinity. Subsequently, the left iRED of the triple iRED is turned on to calculate the distance to the signal image, and the right iRED is turned on to calculate the distance to the signal image. The distance of the subject in three directions is obtained by the above procedure.

In step # 112, when the taking lens 32 is on the telephoto side, the depth of the subject becomes shallower.
Since the probability that the subject exists at a long distance is large, the distance measuring ability on the long distance side is required. Therefore, in principle, a passive distance measuring method is used in which the distance measuring ability does not decrease even at a long distance.

In general, in the passive distance measurement, an image of a subject illuminated by strong light such as sunlight is accumulated.
The maximum accumulation time t1 required for signal accumulation can be set shorter than the distance measurement by the active method. Further, in the distance measurement by the passive method, since the signal of the entire width of the sensor array as the light receiving means is captured by one accumulation, it is possible to measure a subject in a wide range as shown in FIG. 5B. There is no need to divide the distance measurement range and perform multi-point distance measurement. That is, it is possible to sufficiently cope with the one-point distance measurement using the passive method. Therefore, the time required for the distance measurement is shorter than the distance measurement time by the active method.

In the next step # 113, since there are a number of subjects that are difficult to measure by the passive method, a central one-point distance measurement by the active method is also used. Therefore, if the same distance measurement time as in step # 111 is permitted, the time (t1) required for distance measurement in information step # 112 is short, and the maximum accumulation time t2 here is t2 = 3 × t3−. It can be set to t1. That is, (分 (3-t1
/ T2) ((3) times), it is possible to measure the distance to a subject that is farther away.

In the next step # 114, the distance to the subject is selected from the plurality of obtained distance measurement results. As a specific example, in the case of going through the above step # 111,
Of the results of the distance measurement to the object in the three directions determined here, the main object is generally often located at a short distance, so the distance measurement result indicating the shortest distance is selected as the distance to the object.

In the case of going through steps # 112 and # 113, a more reliable distance measurement result is selected from the results of distance measurement by the passive method and the active method obtained in these steps. However, it is known that, when a distance is measured for a subject that repeats the same contrast pattern by a passive method, an erroneous distance measurement result, that is, a highly reliable and short distance measurement result is obtained.
However, if the distance measurement target is a short distance object, the distance can be reliably measured by the active method, and if the reliable short distance measurement result is obtained by the passive method, Ignore and select the result of active ranging.

According to the above-described embodiment, when the set focal length is on the wide-angle side, 3
Accurate ranging information is obtained by point ranging, and on this wide-angle side, the active ranging distance is sufficient, so the passive ranging is not performed and the ranging time is reduced accordingly. Like that.

On the other hand, on the telephoto side, the distance is measured at the central point by the active method, and the maximum signal accumulation time is set to be approximately three times the maximum signal accumulation time per direction on the wide-angle side. To improve the distance measurement capability.
On the telephoto side, since a long distance measurement capability is required, the distance measurement by the passive method is also used to select the more reliable distance measurement result.

(Modification) In the present embodiment, the range finder in which each of the active system and the passive system is used as a light receiving means and the like is described as an example. It is needless to say that the same effect can be obtained also in a hybrid distance measuring device configured by combining the distance measuring device of the above and a passive type distance measuring device.

Also, in the passive distance measurement, multi-point distance measurement is possible, and distance information can be obtained by appropriately selecting the distance.
Alternatively, final ranging information may be obtained by evaluating each ranging information by weighting or the like.

The present invention can be applied to various types of cameras such as a single-lens reflex camera, a lens shutter camera, and a video camera, optical devices other than cameras, and other devices, and further to those cameras, optical devices, and other devices. The present invention can be also applied to devices that include these components, or components that constitute them.

[0040]

As described above, according to the present invention,
For example, when the focal length information of the lens is on the wide-angle side, since distance measuring capability at a long distance is unnecessary, the distance measuring information is calculated using active type distance measuring means. However, the distance measurement information is calculated by the passive distance measurement means with a small decrease in the distance measurement ability, and the passive distance measurement means has a weak distance measurement target. The distance measurement information is also calculated at the center distance measurement point by the multi-point distance measurement means, so that the final distance measurement information is obtained. Thus, it is possible to provide a distance measuring apparatus capable of obtaining accurate distance measuring information.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of a main part of a camera having a hybrid distance measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of a camera according to one embodiment of the present invention.

FIG. 3 is a flowchart illustrating an operation of the camera according to the embodiment of the present invention.

FIG. 4 is a flowchart showing details of the operation of step # 102 in FIG. 3;

FIG. 5 is a diagram showing a distance measurement range viewed from a finder in the camera according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light-receiving means 2R, 2L Sensor array 3R, 3L Signal accumulation circuit 4 Signal changeover switch 6 CPU 9 Memory circuit 10 iRED drive circuit 11 Triple iRED 20 Projection lens 21R, 21L Light reception lens 33 Focal length changeover switch

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI G03B 7/28 G03B 3/00 A

Claims (6)

[Claims] 1. A method according to claim 1, further comprising: projecting light toward the object to be measured, and receiving reflected light of the projection light from the object to be measured.
In a distance measuring apparatus having an active distance measuring means for calculating a distance to an object to be measured and a passive distance measuring means for calculating a distance to the object to be measured by light from the outside, A distance measuring device, comprising: a control unit that controls driving of the active distance measuring unit and the passive distance measuring unit according to use conditions. 2. The distance measuring apparatus according to claim 1, wherein the use condition of the optical device is information on a focal length of a lens. 3. The method according to claim 1, wherein at least the active distance measuring means of the active distance measuring means and the passive distance measuring means is capable of measuring distances at a plurality of points on a screen. The distance measuring device according to claim 1. 4. The control means calculates distance measurement information using the active distance measurement means when the focal length of the lens is on the wide angle side, and calculates the active distance measurement information when the lens is on the telephoto side. 3. The distance measuring apparatus according to claim 2, wherein the distance measuring information is calculated using both the distance measuring means and the passive distance measuring means. 5. The control means calculates distance measurement information by multi-point distance measurement using the active type distance measurement means when the focal length of the lens is on the wide angle side, and when the focal length of the lens is on the telephoto side, The distance measurement information is obtained from the center distance measurement point using the active distance measurement means, and the distance measurement information is obtained using the passive distance measurement means. The distance measuring apparatus according to claim 3, wherein distance information is calculated. 6. The distance measuring device according to claim 1, wherein the light receiving means for receiving the light from the object to be measured is constituted by a skim CCD having a pair of a sensor array composed of a plurality of photoelectric conversion elements. apparatus.